<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        padding: 0;
        margin: 0;
      }

      article {
        width: 600px;
        position: relative;
        height: 150px;
        margin-left: 100px;
        margin-top: 100px;
        outline: solid 5px silver;
        display: flex;
        padding: 20px;
      }

      article div {
        outline: solid 5px blueviolet;
        text-align: center;
        font-size: 28px;
        line-height: 5em;
        flex: 1 0 100px;
      }
    </style>
  </head>
  <body>
    <article>
      <div>1</div>
      <div>2</div>
      <div>3</div>
    </article>
  </body>
</html>
